This invention is directed to lubricant compositions containing small additive concentrations of reaction products which possess excellent multifunctional antiwear and friction modifying activity. This invention is also directed to such additives as novel compositions of matter.
The need for antiwear or friction reducing modifiers in lubricating oils to meet the ever changing requirements of modern engines is well known. Various materials and various techniques have been proposed.
The use of oxazolines is known for their surfactant and lubricity properties when formulated into lubricating oils and for their water scavenging and dispersant characteristics when blended into fuels.
The use of phosphorus containing lubricating additives has also found widespread use. Phosphonates have been found to be lubricity and antiwear agents as exemplified by U.S. Pat. No. 4,356,097 which describes the use of dihydrocarbyl phosphonates and lubricant formulations.
U.S. Pat. No. 3,920,567 describes quaternary salts formed as the reaction product of an alkyl phosphonate and a hydroxyalkyl oxazoline as useful antiwear and extreme pressure agents in lubricating oils.
In accordance with the present invention the use of novel zwitterionic (internal) acid phosphate salts of oxazolines in lubricants provides effective antiwear activity, and friction reducing characteristics. Furthermore these unique internal oxazoline-derived acid phosphates not only provide greater antiwear activity than traditional acid oxazolines but have greater potential friction reducing activity than previously reported with prior art acid phosphates. The exceptional surface activity of these novel additives, coupled with the oxazoline moiety, apparently provide the basis for the significant synergistic friction-reducing activity.